1. Field of the Invention
The invention proceeds from an electronic instrument according to the preamble of patent claim 1. Particularly in power engineering, electronic instruments are often exposed to atmospheric conditions. In this case, condensing water vapor may appreciably impair the operating capacity of the electronic components present in the instrument.
2. Description of Background
An electronic instrument of the type initially mentioned is described in DE 42 10 979 C2. This instrument contains a printed board 3 fastened in a two-part watertight housing 1 and capable of being fitted with electrical and/or optical elements. The housing interior communicates with the outside air via a duct 20 and a ventilating element 23 which closes off the duct and which is composed of a textile diaphragm made of gas-permeable and liquid-tight PTFE. This prevents water from infiltrating into the housing interior and, at the same time, ensures sufficient gas exchange. A transparent cover 25 screens off an electrical connector 2 of the printed board and the diaphragm against environmental influences.
DE 43 13 776 C1 discloses a socket-shaped ventilating device for an instrument housing. This ventilating device has a two-part splashwater guard with a tubular socket 3 and with a bowl 4. The tubular socket and the bowl have shaped into them a labyrinth which connects the housing interior to the outside air, allows water to escape from the housing interior and prevents splashwater from penetrating. Dust is kept away from the housing interior by a dust filter arranged in the tubular socket 3.